Hope I've not violated etiqutte by posting here and on the V6 board but wanted the best shot at some good help.

I have a 97 with the 4.2L motor and about 65,000 miles on it.

Last week it started running horribly rough and backfired some. I took the first line of attack and put in Heet. That made a small improvement but still rough. I then changed the fuel filter which brought even more improvement. I then swapped the PCV out and it cured the problem... except between 1,500 and 2,000 RPM. It's not bad but it has a "shudder" right in that area. Above and below runs great. Speed isn't relevant to it happening only RPM.

The check engine light will flash sometimes but doesn't stay on. My local dealer demands appointments and won't run the codes for me. The only diagnostic code readers I can find are $200 so I don't know what the engine thinks is wrong.

Any ideas? This only in a certain range trouble has me worried.

 

possibly transmission shudder. do a search and see if any of the descriptions sound like your problem. good luck!

 

Thanks Jim. I was hunting Zebras when I should have been looking for horses.

New set of plugs and wires cured it.

 

I had the exact same sysmtoms in my Accord. A seemingly transmission shudder regardless of speed at about 2000 rpms. It turned out to be blocked egr ports.

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2000 4x4 XLT S/C, 5.4L,3.55 LS, Towing Package, Rear Slider

 

I had suspected an EGR problem because the symptoms were so similar but I had good vaucum.